1. Technical Field
The present invention relates to an optical device which forms an optical image by modulating an incident luminous flux in accordance with image information, and to a projector equipped with the optical device.
2. Related Art
To date, a projector which forms an optical image in accordance with image information, and projects the optical image enlarged onto a screen or the like, has been known. As this kind of projector, a projector has been known which includes a light source, an optical modulation device which modulates a luminous flux emitted from the light source in accordance with the image information, and a projection lens which projects the modulated luminous flux as the optical image.
In recent years, a so-called 3 LCD projector, which has improved an image quality and a color reproducibility of a formed image, has been conceived. This kind of 3 LCD projector includes a color separation optical system, which separates a luminous flux emitted from a lamp serving as the light source into color light of three colors of red (R), green (G) and blue (B), a plurality of liquid crystal panels, provided for each of the separated color lights, serving as the optical modulation device which modulates an incident color light in accordance with the image information, and a synthesizing optical device which forms the optical image by synthesizing the color light modulated by each liquid crystal panel (for example, refer to JP-A-2004-198596 (pages 5 to 7, FIG. 1)).
In the projector described in JP-A-2004-198596, a polarizing plate main body which adjusts a polarization direction of a light, a pair of glass substrates which sandwich the polarizing plate main body, a frame which holds the polarizing plate main body and the pair of glass substrates, and a retaining spring being provided, they integrally configure a polarizing plate. Then, the polarizing plate is disposed, by means of an attachment plate which attaches the liquid crystal panel to a luminous flux incidence surface of a cross dichroic prism serving as the synthesizing optical device, between the liquid crystal panel and the cross dichroic prism.
However, with the projector described in JP-A-2004-198596, as the number of parts attaching the polarizing plate main body to the cross dichroic prism increases, there is a problem that a configuration of the projector and a manufacturing process become complicated.
In response to this, a configuration is considered in which the polarizing plate main body and the pair of glass substrates sandwiching the polarizing plate main body are adhesively secured and, of the pair of glass substrates, a glass substrate disposed on a luminous flux irradiation-side of the polarizing plate main body is affixed to the luminous flux incidence surface of the cross dichroic prism. In this kind of case, although it is possible to reduce the number of parts involved in attaching the polarizing plate, in the event that the liquid crystal panel is attached via the attachment plate to a luminous flux incidence surface of the polarizing plate main body, adhesive layers interposed between the liquid crystal panel and the cross dichroic prism increase. For this reason, as well as a position adjustment of the liquid crystal panel with respect to the cross dichroic prism becoming difficult, there is a problem in that displacement of the liquid crystal panel can occur due to a weight of the liquid crystal panel etc. along with an aging change of the adhesive layers.
In response to this kind of problem, there has been a demand for a projector which can suppress the displacement of the liquid crystal panel while restraining the increase in the number of parts.